Science Buddies: "Ask an Expert"

Hello...I am assisting my daughter in her science fair project. We read over again the directions for the project: the Skinny on Moisturizers: Which works Best to Keep Skin Moist?

Jell-o is the recommended medium for this project. In another posting I saw the mother had the same question. How can Jell-o that is placed in petri dishes followed by the desired moisturizer work? I would figure once the moisturizer would be placed on the Jell-O it would act like a barrier and maybe prevent it from oozing or melting, causing the science project to not work. It seems to me it would need to be placed back in the refrigerator. We have a basement and it is quite cold down there...but will a certain temp affect the outcome of the Jello and project. I am maybe thinking we should look for another medium? Do you have a suggestion for another medium....and if not does it matter if the jello is colored and not clear? We have to fill 18 petri dishes and want to make sure this works well. Your assistance would be appreciated as we start the project this weekend.

Thank you.

Dana

Hi Dana,

In this project, you make up the Jell-o, pour it into the petri dishes and let the Jell-o set up in the petri dishes in the refrigerator. Once they have set properly, the Jell-o will not ooze or melt, even when it is at room temperature. What does happen is that as the dishes are left at room temperature, the water in them begins to evaporate and the plates dry out. This process will also happen in the refrigerator, but it would take MUCH longer (because less water will evaporate at the colder temperature). So what you would want to do is make the petri dishes and let them set in the refrigerator. Once the petri dishes have completely set (I'd probably let them set overnight), you can remove them from the refrigerator and smear on your moisturizer (or not in the controls). Then, the petri dishes can sit at room temperature for a set amount of time until you are ready to test them for how much moisture they have lost (as described in the project protocol). Your basement should be fine for this, but again, a cooler location will likely lead to less moisture lost and therefore potentially less difference between your experimental moisturizers and your controls, so I'd probably just leave them out on a counter somewhere. One caveat, while the jell-o should stay solidified at room temperature, if you make it too warm, it will definitely melt, which is not the outcome you want, so don't put it near a heat source (like the oven), or in a direct stream of sunlight or something where it might get TOO warm.

Hope this helps,
JMP

P.S. The colored jell-o will be fine. By clear, they mean that it should be translucent and not opaque (i.e. you can see something through it), but it's fine if it's lime flavored (or something like that).

Hi JMP,

Thank you so much for your response. It is very helpful. My daughter is anxious to get this going and this clarifies our questions.

Have a good day.

Dana